Process of preserving milk in dry form.



No. 7l2,545. Patanted Nov. 4, I902.

- J. A. JUST.

PROCESS OF'PRESERVING IILK IN DRY FORM.

(No Model.)

' INVENTOR 7444 a f I BY WITNESSES gum,

UNITED STATES PATENT OFFICE.

JOHN A. ins'rfor SYRACUSE, NEW YORK.

PROCESS OF P'RESESVING MILK IN DRY FORM.

SPECIFICATION forming part Of Letters Patent No. 713,545, dated November4 1.909.

Application filed Kay 23. 1902. Serial lo. 108,814. (No specimens.)

To all whom it may concern Be it known that I, JOHN A. JUST, a citizenof the United States, residing at Syracuse, in the county of Onondagaand State of New York, have invented a certain new and useful Process ofPreserving Milk and Milk-Like Products in a Dry Form; and I do herebydeclare the following to be a full, clear, and exact description of theinvention, such as will onable others skilled in the art to which itappertains to practice the same.

My invention relates to the preserving of milk and milk-like products ina dry form by expelling the water and maintaining the other ingredientsnormal and unchanged, so that -by the addition of water to the dryproduct complete milk is reproduced.

The essential steps of my process are delivering the milk in a limitedbulk onto a surface heated to a high temperature of from 212 to 270Fahrenheit, so that it boils violently without separation of the casein,and then drawing this milk in a film onto a heated surface, from whichthe film is instantly removed when apparentlystill moist and somewhattenacious. The sheets, which come off when cool readily crumble and canbe powdered, giving a good quality of dry preserved milk. I To make asuperior product, I prefer, initially, in case of skim-milk to cut offthe excessive acidity to about neutral or a shade on the acid side andin case of whole milk to a shade on the alkaline side by the addition oflime or a soluble lime salt. In case of whole milk I also add alkalinehypochlorite to take care of the volatile fatty acids and to preventfuture rancidity of the product.

To understand the effect of the different steps of this process, thenormal ingredients of milk must be' considered and the injurious effectson them produced by ordinary modes of treatment heretofore practiced,which I have guarded against.

Milk consists on the average of the following constituents insubstantially the following percentages, there being at least 12.5 percent. of these solids in whole milk: milk albuminoids, 3.5; milk-fat,3.5; milk-sugar, 4.6; salts or inorganic substances besides the water,.7 to v.9. The albuminoids'cousist principally of'casein in the form ofcalcic caseinate,evidentlya dicalcl'c caseinate. The remainder of thealbuminoids are'principally lacto-albumin and lacto-globulin. The latteris so small in amount as to be disregarded.

The former is presentin the milk in perfect solution, The particles ofthe casein are held in the solution in a highly swelled condition, whichgives to the milk the-appearanceof a solution. This condition and themaintaining a balance of the constituents requires the normality of themilk salts. On heating the milk the calcium citrate present in milk as anaturalconstituent tends to precipitate. The tricalcic phosphate, whichthe calcium citrate holds in balance to the casein, changes itsposition, and the casein at once assumes an insoluble form. Milkcontains salts of the posed, in the air, a skin is formed on thesurface. ,On removing the skin thus formed a new skin forms. This maycontinue until fifty or more skins are removed, and thus all the albuminand casein are rendered more or ert-y of the casein is entirelydestroyed and the solubility of the milk-sugar is partially or whollylost. Even evaporation of milk in less insoluble and Femoved in thiscoagulated "form, by 'which the important swelling'propa partial vacuumhas a similar action on the v albuminoids of milk under certainconditions. For this reason allprevious attempts were not successful indrying milk, either in partial'vacuo'or in the atmosphere, to produce asatisfactory dry milkpowder, one that can be restored to milk onaddition of water with the milk constituents intact.

M ilk-fat is the most complicated fat known, consisting of from nineto'twelve glycerides, or about ninety-one per cent. of fixedfats, andatleast four volatile fatty acids, to the amount of nine per cent. fatsin emulsion, a 'sary'.

To hold the milkslight alkalinity is neces- 95. I have discovered a modeof-adjnstment which overcomes the former ditficulties that arose in theattempt to reduce milk to the dry state and have produced a stable dryproduct in which the milk constitutents are preserved in their normalcondition. This process will be best understood by remember: ing thatthe ingredients of milk which most readily induce a change in theattempt to dry the milk are the inorganic substances and the milk-sugar.For instance, by the initial acidity arising from milk-sugar (lacticacid) the balance of the salts is overcome and insoluble caseincompounds are separated, (spontaneoussouring of milk.) I firstneutralize the necessary acidity of the milk or milk-like liquids, sothat themilk still reacts slightly on the acid side. This can be donesatisfactorily by a solution of calcium oxid (OaO) in calcium chlorid,(CeC1,,) representing an excellent formof soluble lime salts withavailable CaO. (At centigrade a solution of (JaCl specific gravity 1.138dissolves 6.37 per cent. of CaO.) But I'find the use or the double saltof sodium and calcium citrate, a salt natural to milkand present thereinin its normal state, very desirable and advantageous. The function ofcalcium citrate in milk is to keep the tricalcium phosphate in solution,and thus maintain the normal casein compound intact. This function mustbe retained, so that after drying and redissolving the dried product thefinely-subdivided casein particles again assume-their swelled condition,showing the true nature of the dicalcic caseinate fully preserved, as itoriginally existed in milk before drying. This sodium calcium citratedoes not precipitate on heating, and therefore holds up the tricalcicphosphate and the casein, taking the pla :e of the natural calciumcitrate, which does precipitate. In order successfully to preserve themilk-fat and to take care of the unsaturated- .oleic acid and volatilefatty acids and prevent rancidity, the volatile fatty acids should befixed and the oleic acid saturated with a suitable substance. I findthat an alkaline hypochlorite answers best for this purpose, the amountrequired being exeeedinglysmall,

but should beequivalent to the amount of volatile fatty acids present.These reagents that is, the calcic chlorid containing calcic oxid insolution or thedouble salt of sodium and calcium citrate, or both, andthe alkaline hypochloritemay be mixed with the milk by any desirablemeans; but as thisis 7 not an easy matter so to incorporate them theymay be mixed mechanically. by first adding'the reagents to a limitedquantity of milk, mixing it therein by hand, and then delivering thismixture to the bulk of milk to be treated, which has been previouslyweighed and is contained in a store-tank in order to fix the requisiteamounts of reagents in proportion to the initial acidity as-thevarlying. condition of the milk may demand.

he mass is thenmixed mechanically and forced from the tank through anejector by steam or air pressure or in any suitable way ance andequilibrium of the milk constituents when reduced to a dry form issmal-L. and on adding water milk is again restored. .From the tank themilk treated with the re agents or adjusted milk is continuouslyconducted and delivered -to a suitable retainingsurface heatedcomparatively to a high dc gree, at least 212 Fahrenheit, and preferably'somewhathigher, but not to exceed Q7 0 Fahrenheit as a maximum. Themilk upon being brought into contact with the heated surface boils upviolently, supported and dancing continuously, as it were,'on a steamcushion between the hot metal and the body of the milk without formingany sign of skin on the surface, thus preserving the casein fully in itsnormal condition through this stage.

From this heated surface, which I call the retainer, the milk 'ormilk-likesolution is drawn in a film onto a similarly-heated surface,from which the film is instantly scraped or removed while apparentlystill moist and somewhat tenacious, coming off in sheets,

which on cooling crumble readily and can be powdered. The dried milk issterilized by the process.

By this process and new mode of heating and adjusting the condition ofthe. salts of milk the salts are maintained in balance and inequilibrium, so that the normal and important swelling up quality of thedicalcic caseinjate (as casein is supposed to exist in normal milk) ispreserved unchanged. This apparently damp condition of the film whilehot is due to the retention of a portion of the water of crystallizationbythe milk-sugar, to which it clings tenaciously and disappearsinstantly on cooling of the removed film,whieh is then, as aforesaid,easily reduced to pow-.

The'retention of this portion of water der. prevents any change in themilk-sugar. The development of bitter and burnt taste and change incolor is avoided, and this delicate ingredient is dried at a hightemperature.

, In the drawings accompanying this specification is shown a desirableform of apparatus which may be employed to carry out continuously my newprocess but it will be understood that other forms may also be employed,as, the successful carrying out of the process does not depend upon aparticularly-con structed apparatus.

Figure 1 is a vertical cross-section of the apparatus, and Fig. 2 avertical longitudinal section taken between the cylinders.

In the views the numerals 1 1 indicate two contacting metallic cylindersjournaled in suitable supports and rotated by any well-' -Fahrenheit.

to the amou'nt drawn down in a film on the surfaces of the cylinders asthey rotate, so that.

a limited amount of milk may be constantly boiled violently in theretaining-receptacles formed by the upper adjacent portions of thecylinders between the end pieces and 10. Scrapers or'kuives 12 12 areprovided to remove the dried film from the cylinders, and receptacles 1212 are placed in position to receive the same.

It will be noted that .the portions of the cylinder-surfaces marked A Aconstitute the retaining-surface, on 'which the limited amount of milkis first boiled violently, and that the portions marked B B constitutethe similarly-heatedsurface, on which the milk is drawn iua film.-

Myprocees may be applied either to the drying of skim-milk or of wholemilk, except that as there is no fat in skim-milk .the alkalinehypochlorite is not needed. My process may also be applied forpreserving milk-like roducts-t'or instanee,-the mixture of curd wet ordry) with skim-milk rendered slightly and preserved by my process arestable and ca bleof being exported into any climate. Th :dry whole milkmay be compressed into tablets of any suitable size-for instance, twoand one-half ounces-for mixture with a pint of water. H 5p 1 Having thusdescribed my invention, what I-claim, and desire to protect by LettersPat- I out, is 1. The .milk so as to preserve it in dry'form,consisting, first; in quickly concentrating the milk by violentlyboiling it, the concentratsl milk in a lilm onto face heated to atemperature in excess 2. The herein-described process of treating milkso as to preserve it in dry form, consisting, first, in violentlyboiling the milk in lim ited quantities on a surface heated to atemperature in excess of 212 Fahrenheit and, second, drawing the milkina film onto a surface heated in excess-of 212 Fahrenheit to dry themilk, third, quickly removingaire solution,

alkaline, thus producinga highly-nitrogenous herein-described processoftreating and, second, drawing dried milk film from the latter-surfacewhile still apparently slightly moist.

' 3. The herein-described process of preserv-. ing milk in a dry form,consisting in, first, Y continuously delivering the milk ontoa surfaceheated to a temperature in excessof 212, but not over 270 Fahrenheit, sothat a limited amount is retained thereon and violently boiled, second,withd rawing the milk, at substantially its delivery rate, in a film,onto a surface also heated to a temperature in excess of 212, but notover 270 Fahrenheit, finally, quickly removing the'dried film whilestill apparently slightly moist, and, last, reducing the dried film topowder.

4. The herein-described process of preserving milk in a dried formconsisting in, first, adding to the milk to be dried a small amount ofsoluble lime salts, second, boiling the milkv on a surface heated to atemperature in excess of 212, but -not over 270 Fahrenheit, third,drawing the milk therefrom in a film onto a surface also heated to atemperature in excess of 212, but not over 270 Fahrenheit, and quicklyremoving the dried film of milk from that surface. 1 a V 5.Theherein-described processof preserv.-. ing whole'milk in a dry form,consisting in, 5 first, adding to the milk small amounts of a calciumoxid dissolved in a ealcium-chlorid of sodium calcium citrate, and-of analkaline hypochlorite, second, violently boiling-the milk on a surfaceheated to a tam perature in excess of 212, but not over 270 Fahrenheit,third, drawing the milkin a'film onto a surface also heated to atemperature in excess of 212, butnot over 270 Fahrenheit and quicklyremoving the dried film.

6. The herein-described process of treating" milk so as to preserve itin a dr'y'form', consisting', first, in thoroughly mixing with a limitedamount of the milk a small amount of soluble lime salts, second, addingsaid mix ture to the entire bulk'of milk to be dried, third, violentlyboiling the milk on a surface" heated to a temperature in excess of 212,but not over 270 Fahrenheit, fourth, drawing the milk in a'film ontoasurface also heated to a temperature in excess of 212, but not over, 270Fahrenheit, and quickly scraping the driedfilm from the surface. Y

7. The herein-described process of preserving 'milk in a dry form,consisting in, first, no adding to the'milk a small amoun't'of sodiumcalcium citrate, second, violently'boilin'gthc: milk on a. surfaceheated to a tern ratnre in excess of 212, but not over'270 ahrenheit,third, drawing .the milk in a fllm onto a sur face also heated'to atemperature in excess of 2l2,bu t not ever 210' l fahr'enheita' dquickly;

removing the dried 1am. 1 v I "In testimony whereof I alli'x'myaignature in presence of two witnesses.- i.

" -"JOHN A. JUST.

"Witnesses:

Wrmm Ooncom Hnm, Sntou 8. WasrrfiIo-rou.

